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Metals I: Metals Preparation and Manufacturing
Published in Ronald Scott, of Industrial Hygiene, 2018
Alternatives to the traditional methods described above include lost wax (investment) casting and lost foam (evaporative pattern) casting. In each case an expendable pattern is molded. Wax patterns are coated to form a temperature-resistant rigid form filled with the wax pattern. The wax is melted out of the form (shell mold), which is then used to cast the product. The shell mold is then broken off the product. In the lost foam method a pattern is made of styrofoam. This is packed in sand. On pouring the molten metal the foam vaporizes and the vapors diffuse out through the sand.
Motor Frame Design
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
As one of the oldest known manufacturing techniques, casting still remains a highly efficient and cost-effective manufacturing process today. Modern advances in casting technology have led to a wide array of specialized casting methods. In manufacturing industries, four main casting methods are commonly used to make a variety of cast products—die casting, sand casting, permanent-mold casting, and evaporative pattern casting (EPC)—each having its own unique fabrication advantages and limitations.
Investigation of ablation studies of EPS pattern produced by rapid prototyping
Published in Virtual and Physical Prototyping, 2018
Ranjeet Kumar Bhagchandani, Sajan Kapil, Pushkar Kamble, K. P. Karunakaran
Conventional investment casting (lost wax casting) involves a complex stage of de-waxing the consumable wax pattern prior to pouring molten metal. While in evaporative pattern casting (EPC) process, expanded polystyrene (EPS) is used for the consumable pattern, which starts evaporating as soon as molten metal is poured. Guler et al. (2011) proposed a novel approach for eliminating the inadequacy of lost wax casting, where EPS was used as a sacrificial pattern in investment casting and was removed using acetone. Fabrication of complicated functionally bi-metallic castings proves the capability of the EPC process (Jiang et al. 2013, Jiang et al. 2015, Jiang et al. 2016). Conventional EPS pattern forming needs three steps: making a pre-puff of appropriate density via pre-expansion of expandable polystyrene beads followed by stabilisation or aging and finally moulding of the foam beads into the desired pattern shape. The process demands both complicated tooling (i.e. dies), as well as controlling multiple parameters to produce acceptable quality patterns. Rapid prototyping (RP) facilitates exploring unconventional pattern-making, which involves heated wire/ribbon-based cutting tool and is used for EPS carving to achieve very high feedrate with low cutting forces. Wire slicing is fast and accurate enough in production of bulk qualitative EPS patterns. Chen et al. (2013) summarised foaming, moulding, manual cutting, CNC machining and RP in existing processes. Hot-tool cutting is a resolution for rapid manufacturing of EPS patterns with complex geometries, sizes and profiles, facilitating substantial reduction in time consumption and power requirement. The slicing process entails a cutting element (wire), whereby electric current is passed, and thus altering the physical properties of the foam. Characterisation of diverse EPS plastic cutting has been formerly scrutinised by researchers (Mehta et al. 1995, Aitchison et al. 2007). The efficacy of slicing process could be elucidated by the dimensional accuracy of the end product, which successively depends on the kerfwidth, stipulated as the width of the material removed during cutting process. Kerfwidth is directly proportional to the offset given to the tool and is inversely proportional to the accuracy achieved for intricate shape.